The sheet stacking system discharges a sheet to one of a first stacking apparatus including a first stacking tray and a second stacking tray, and a second stacking apparatus including a third stacking tray, executes one of a first discharging method and a second discharging method, the first discharging method for moving, after a sheet is discharged to the first stacking tray by executing a job, the sheet which has been discharged to the first stacking tray to the second sheet stacking tray and discharging a sheet to the first stacking tray of the first stacking apparatus by executing the job, and the second discharging method for, after a sheet is discharged to the first stacking tray by executing the job, discharging a sheet to the third stacking tray of the second stacking apparatus by executing the job.